1. Field of the Invention
The present invention relates generally to compression of image data and, more particularly, to adjusting the rate of compression.
2. Description of the Related Art
Transmission and handling of message data is an important function that must be carefully and efficiently performed. For example, a health care delivery system such as a hospital or medical center will receive message data of many different types. It is critical for the health of patients that message data is delivered to appropriate medical staff, with sufficient data integrity to be useful to the staff member. Message data may include image information, for example, image information from a laboratory examination such as an X-ray, computer tomography (CT Scan), magnetic resonance imaging (MRI), or other laboratory examination. The image information can be in a variety of data formats, such as JPEG data, bitmap data, TIFF images, and the like.
Digital representation of image information often requires large amounts of data, making transmission and storage of image data challenging and expensive. Data compression techniques have been developed to reduce the amount of data that must be transmitted and stored. In brief, data compression refers to techniques that represent data files in a format that requires less “bits” than the original data file. The “compression rate” refers to the number of bits in the compressed data file as compared to the number of bits in the uncompressed data file.
Known data compression techniques may be divided into two broad categories, lossy compression and lossless compression. Lossy compression involves compression of a data file that results in the loss of some of the original information when the original data file is reconstructed from the compressed file. In other words, when the original data file is reconstructed from the lossy compressed file, there are differences, or errors, between the reconstructed file and the original file. A typical goal of lossy compression techniques is that the differences, or errors, in the reconstructed data file are tolerable with varying amounts.
Lossless compression involves compression of a data file that results in no loss of original information when the original data file is reconstructed. In other words, lossless compression techniques compress the original data file in such a way that when the original data file is reconstructed from the compressed file there are no differences, or errors, between the reconstructed file and the original file.
Generally, lossy compression techniques can achieve a higher compression ratio, resulting in smaller compressed file sizes, as compared with lossless compression. However, there is usually degradation in the reconstructed data file using lossy compression, while there is no significant degradation in the reconstructed data file using lossless compression.
Use of data compression techniques on medical image files can be beneficial in reducing both the storage capacity and transmission bandwidth required for large image files. For example, digital radiology benefits from compression algorithms by reducing both image storage and transmission costs. However, the amount of compression that can be achieved with medical image files is limited by the amount of “loss” or errors, if any, that are acceptable in the reconstructed image, i.e., there may be resolution or loss specifications set by the medical application for the data. To illustrate, because radiology imagery may be critical for the health of patients, it is important to maintain the image “quality” which means that generally less error and therefore less compression can be tolerated. This limits the storage and transmission benefits achievable with higher amounts of compression.
From the discussion above, it should be apparent that there is a need for a system and techniques that can improve data compression of image data files for reduced consumption of system resources while maintaining sufficient data fidelity. Other problems with the prior art not described above can also be overcome using the teachings of the present invention, as would be readily apparent to one of ordinary skill in the art after reading this disclosure.